Rio Ferdinand has raised two questions about Manchester United's potential signing, Lisandro Martinez. The Red Devils legend claims the Argentine's height and pace could be an issue in the Premier League.Manchester United are reportedly close to signing Martinez from Ajax after a fee was agreed on Friday. The Argentine is set to cost €55 million and will sign a deal until 2027.Fabrizio Romano@FabrizioRomanoLisandro Martínez to Manchester United, here we go! Full agreement in place between Man United and Ajax for package up to €55m. Lisandro will sign until 2027, documents now approved. #MUFCDeal done - meeting in Amsterday on Wednesday was the key step. Ten Hag, big factor.18548234120Lisandro Martínez to Manchester United, here we go! Full agreement in place between Man United and Ajax for package up to €55m. Lisandro will sign until 2027, documents now approved. 🚨🔴 #MUFCDeal done - meeting in Amsterday on Wednesday was the key step. Ten Hag, big factor. https://t.co/qyYskmgNMUWhile speaking on his YouTube channel FIVE, Ferdinand claimed he heard good things about Martinez. However, he raised concerns about the player's height and pace and said:"The more I've looked into him and the vibes and the stories I'm hearing and the mutterings from different people–it gets better. I listened to an interview with Jurrien Timber, the young player that United were looking to sign, the centre back Martinez played alongside at Ajax. He was basically saying, 'When I'm not on my game and a bit out of concentration, Martinez always shouts at me, he always swears at me in in his language and gets me going.'"Ferdinand added:"I've been shouting about the character element for a long time, and from what I'm hearing from various people, Timber being one of them, is that he has the character, he's a leader, he demands of other people, and he's somebody who wants to get physical and very aggressive but who can also play. If you're going to ask is there any question marks about him, I think it would be his height and his pace would be the only two."Lisandro Martinez to play as a defender and midfielder at Manchester United?Rio Ferdinand spoke about the different positions Martinez could play and claimed it could be a mix of both when the time comes.Fabrizio Romano@FabrizioRomanoHere’s Lisandro Martínez together with his agent flying to Manchester from Amsterdam. Deal completed, club announcement to follow soon. Contract signed until June 2027. 🛩 #MUFCManchester United are set to unveil Lisandro as 3d signing after Malacia and Eriksen.384033989Here’s Lisandro Martínez together with his agent flying to Manchester from Amsterdam. Deal completed, club announcement to follow soon. Contract signed until June 2027. 🔴🛩🇦🇷 #MUFCManchester United are set to unveil Lisandro as 3d signing after Malacia and Eriksen. https://t.co/UNORC0zgahHe said:"I think [the positions] will be a mix because he's very comfortable at playing both positions. If it suits them to play him in midfield and they want the extra body, an extra bit of resilience in front of the back four, protection and somebody who knows how to defend in there, then I think they may be utilizing that."Martinez was also a target for Arsenal, but he chose to join Manchester United.